This investigation is interested in understanding the pathogenesis of the morphologic and biochemical lesions in the liver, muscle, pancreas, and other organs induced in young rats by force-feeding diets devoid of single essential amino acids. It is proposed to study the morphologic and chemical changes due to certain single amino acid deficiencies in acute experiments and also the pathologic effects of long term essential amino acid deficiencies. Some of the mechanisms responsible for increased liver lipid and glycogen and for pancreatic acinar atrophy in essential amino acid deficiencies will be investigated. Also, the mechanism by which enhanced hepatic protein synthesis develops in rats force-fed a threonine-devoid diet will be investigated in in vivo and in vitro experiments. The ultrastructural changes in the liver are being investigated in an attempt to correlate morphologic and biochemical events induced in the experimental kwashiorkor-like model.